Semiconductor light-emitting devices including light emitting diodes (LEDs), resonant cavity light emitting diodes (RCLEDs), vertical cavity laser diodes (VCSELs), and edge emitting lasers are among the most efficient light sources currently available. Materials systems currently of interest in the manufacture of high-brightness light emitting devices capable of operation across the visible spectrum include Group III-V semiconductors, particularly binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, also referred to as III-nitride materials. Typically, III-nitride light emitting devices are fabricated by epitaxially growing a stack of semiconductor layers of different compositions and dopant concentrations on a sapphire, silicon carbide, III-nitride, or other suitable substrate by metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or other epitaxial techniques. The stack often includes one or more n-type layers doped with, for example, Si, formed over the substrate, one or more light emitting layers in an active region formed over the n-type layer or layers, and one or more p-type layers doped with, for example, Mg, formed over the active region. Electrical contacts are formed on the n- and p-type regions.
FIG. 1 illustrates a slug 240 for mounting at least one LED to a heat sink, described in more detail in U.S. Pat. No. 7,625,104. LED dice 244 are mounted on a mounting portion 248 of the slug. The slug is formed from a thermally conductive material such as aluminum, steel, or copper, for example. The slug further includes a post 250. The post 250 includes a threaded portion 252 at a distal end of the post. A threaded nut 254 is received on the threaded portion 252 of the post 250.
The slug 240 is shown mounted to a heat sink 270. The heat sink 270 includes an opening 272 for receiving the post 250. A thermally conductive material 249 is disposed between a front surface 274 of the heat sink 270 and the mounting portion 248 of the slug. The slug 240 is secured to the heat sink 270 by engaging and tightening the threaded nut 254, thus causing the mounting portion 248 of the slug to be urged into thermal coupling with the front surface 274 of the heat sink 270. Conductors 260 and 262 extend past the end of the threaded portion 252 of the post 250, and facilitate connection to a current supply for supplying operating current to the LEDs 244.
The heat sink 270 has a cylindrical can-shaped body, which further acts as a light reflector and/or light guide for collecting and directing the light generated by the LED dice 244. The conductors 260 and 262 may be connected to a lighting fixture (not shown) on the ceiling of a room for suspending the LED apparatus. In other embodiments, the heat sink 270 may be a plate, or a heat sink having cooling fins, for example.